1. Field of the Invention
The present invention relates to a reception apparatus, a signal reproducing apparatus using the reception apparatus and a control method thereof. More particularly, this invention relates to a reception apparatus for receiving data multiplex broadcasting, a signal reproducing apparatus using the reception apparatus and a control method thereof.
2. Background of the Invention
In European countries, FM audio broadcast service is initiated to broadcast an audio signal in the form of a broadcast signal added with data concerning broadcast contents. This broadcasting service that just started in European countries is called a Radio Data System (RDS). FM broadcasting based on the RDS (hereinafter simply referred to as "RDS broadcast") will be described below.
As shown in FIG. 1 of the accompanying drawings, a baseband signal of an FM broadcast signal is transmitted in the multiplexed form of a main signal M (sum signal L+R in the case of stereo broadcasting) and a stereo signal S (difference signal L-R), and a stereo pilot signal P is assigned to a frequency band of 19 kHz. This is the same as the ordinary FM stereo broadcast signal.
In the case of the RDS broadcast, a sub-carrier signal SC is assigned to a frequency band of 57 kHz which is three times as high as the frequency of the stereo pilot signal P. RDS data R is modulated by the sub-carrier signal SC.
The RDS data R is composed of grouped digital data as shown in FIG. 2. As shown in FIG. 2, one group is composed of 4 blocks and each block is composed of 26-bit data. Of 26 bits, 16 bits are assigned to practical data representing broadcast contents or the like, and remaining 10 bits are assigned to an error correction code. The 16-bit data in respective blocks are defined individually.
Data transmitted according to the above-mentioned format are mainly as follows:
PS code . . . Character data representing broadcast station name
PI code . . . ID (identification) code of broadcast program, country name code, program code, etc.
TP code . . . Traffic information broadcast station ID signal
TA code . . . Traffic information broadcasting ID signal
PTY code . . . Program content ID code representing contents of news, sports and music of each genre
EON code . . . ID code representing broadcast contents of other broadcast station
The listener can learn the present broadcast contents of a certain broadcast station by using these codes and also can learn broadcast contents of other broadcast station. By using the TP code representing that the traffic information broadcasting is carried out, for example, it is possible to for the listener detect that traffic information is broadcast by a broadcasting station (its own or other broadcasting station) represented by other data (PS code, EON code, etc.) transmitted simultaneously.
Accordingly, it is possible to determine by identifying the RDS data superimposed upon the broadcasting signal of this broadcasting station when the listener listens to FM broadcasting of a certain frequency, for example, whether or not other broadcasting station broadcasts traffic information. Therefore, it is possible to prevent the listener from missing desired information, such as traffic information or the like. of the listener.
When the data based on the RDS broadcasting is used as described above, it is necessary for the listener to constantly listen to FM broadcasting (RDS broadcasting) of any broadcasting station. If the FM broadcasting or RDS broadcasting were not received, RDS data would not be received. For this reason, unless traffic information is broadcast by any broadcasting station for a long period of time when the listener wishes to hear traffic information, for example, the listener should keep listening to broadcasting of other broadcasting content for a long period of time until any broadcasting station starts broadcasting traffic information.
In this case, if no sounds are inhibited from being emanated from the speakers of the receiver by adjusting the volume control under the condition that an FM receiver receives the RDS broadcasting, it is possible for the listener to obtain only the RDS data without listening to broadcast sounds. In this case, however, although the listener learns that any broadcasting station broadcasts broadcasting program of desired contents based on the RDS data, such as traffic information, new or the like, it is not possible for the listener to listen to such broadcasting without operating the volume control. There is then the large possibility that the listener will miss the chance of hearing such desired information while operating the volume control.